Indonesia is the fourth most populous nation in the world. Of its large population, the majority speak Indonesian, making it one of the most widely spoken languages in the world.[5]

Most Indonesians, aside from speaking the national language, are often fluent in another regional language (examples include Javanese, Sundanese and Madurese), which are commonly used at home and within the local community. Most formal education, and nearly all national media and other forms of communication, are conducted in Indonesian. In East Timor, which was an Indonesian province from 1975 to 1999, Indonesian is recognised by the constitution as one of the two working languages (the other being English), alongside the official languages of Tetum and Portuguese.

The Indonesian name for the language is Bahasa Indonesia (literally "the language of Indonesia"). This term is occasionally found in English. Additionally, English speakers sometimes use "Malay-Indonesian" to refer collectively to the standardized language of Indonesia (Bahasa Indonesia) and the Malay of Malaysia, Brunei, and Singapore (Bahasa Melayu).

Map of where Indonesian is predominantly spoken. Dark blue: as a majority language. Light blue: as a minority language.

In 2010, Indonesian had 42.8 million native speakers, and 154.9 million second-language speakers[1] , who speak it alongside their local mother tongue, giving a total number of speakers in Indonesia of 197.7 million.[1] It is common as a first language in urban areas, and as a second language by those residing in more rural parts of Indonesia.

Indonesian is a standardizedregister of "Riau Malay",[9][10] which despite its common name is not the Malay dialect native to Riau, but rather the Classical Malay of the Malaccan royal courts.[11] Originally spoken in Northeast Sumatra,[12] Malay has been used as a lingua franca in the Indonesian archipelago for half a millennium. Although it might be attributed to its ancestor, the Old Malay language (which can be traced back to the 7th century), the Kedukan Bukit Inscription is the oldest surviving specimen of Old Malay, the language used by Srivijayan empire. Since the 7th century, the Old Malay language has been used in Nusantara (Indonesian archipelago), marked by Srivijaya inscriptions and in other inscriptions of coastal areas of the archipelago, such as those discovered in Java. Trade contacts carried on by some ethnic peoples at the time was the main vehicle to spread the Old Malay language, as it was the communication device among the traders. By that time, the Old Malay language had become a lingua franca and was spoken widely by most people in the archipelago.[13][14]

The adoption of Indonesian as the country's national language was in contrast to most other post-colonial states, as neither the language with the most native speakers (in this case, Javanese) or the language of the former European colonial power (in this case, Dutch) was to be adopted, but one with only a small number of native speakers.

In 1945 when Indonesia declared its independence and Indonesian was formally declared the national language, it was the native language of only about 5 per cent of the population, whereas Javanese and Sundanese were the mother tongues of 42-48 per cent and 15 per cent respectively.[15] It was a combination of nationalistic, political, and practical concerns that ultimately led to the successful adoption of Indonesian as a national language. In 1945, Javanese was easily the most prominent language in Indonesia. It was the native language of nearly half the population, the primary language of politics and economics, and the language of courtly, religious, and literary tradition.[16] What it lacked, however, was the ability to unite the diverse Indonesian population as a whole. With thousands of islands and hundreds of different languages, the newly independent country of Indonesia had to find a national language that could realistically be spoken by the majority of the population and that would not divide the nation by favoring one ethnic group, namely the Javanese, over the others. In 1945, Indonesian was already in widespread use;[15] in fact, it had been for roughly a thousand years. Over that long period of time, Malay, which would later become Indonesian, was the primary language of commerce and travel. In addition, it was the language used for the propagation of Islam in the 13th to 17th centuries, as well as the language of instruction used by Portuguese and Dutch missionaries attempting to convert the indigenous people to Christianity.[16] The combination of all of these factors meant that the language was already known to some degree by most of the population, and it could be more easily adopted as the national language than perhaps any other.

Indonesian was elevated to the status of official language with the Indonesian declaration of independence in 1945, drawing inspiration from the Sumpah Pemuda (Youth Oath) event in 1928.[17] Over the first 53 years of Indonesian independence, the country’s first two presidents, Soekarno and Suharto constantly nurtured the sense of national unity embodied by Indonesian, and the language remains an important component of Indonesian identity today. Through a language planning program that made Indonesian the language of politics, education, and nation-building in general, Indonesia became one of the few success stories of an indigenous language effectively overtaking that of a country’s colonizers to become the de jure and de facto national language.[18] It is a unique and somewhat unusual story, especially considering the historical dominance of Javanese; a diverse collection of peoples were able to compromise to hold the nation together. Today, Indonesian continues to function as the language of national identity as the Congress of Indonesian Youth envisioned, and it also serves as the language of education, literacy, modernization, and social mobility.[18] Despite still being a second language to most Indonesian citizens, it is unquestionably the language of the Indonesian nation as a whole, as it has had unrivaled success as a factor in nation-building and the strengthening of Indonesian identity.

Indonesian (in its standard form) is essentially the same language as the official Malaysian and Brunei standards of Malay. However, it does differ from Malaysian in several aspects, with differences in pronunciation and vocabulary. These differences are due mainly to the Dutch and Javanese influences on Indonesian. Indonesian was also influenced by the "Melayu pasar" (literally "market Malay") that was the lingua franca of the archipelago in colonial times, and thus indirectly by other spoken languages of the islands. Malaysian Malay claims to be closer to the classical Malay of earlier centuries even though modern Malaysian has been heavily influenced, in lexicon as well as in syntax, by English. The question of whether High Malay (Court Malay) or Low Malay (Bazaar Malay) was the true parent of the Indonesian language is still in debate. High Malay was the official language used in the court of the Johor Sultanate and continued by the Dutch-administered territory of Riau-Lingga, while Low Malay was commonly used in marketplaces and ports in archipelago. Some linguists have argued that it was the more-common Low Malay that formed the base of the Indonesian language.[19]

When the Dutch East India Company (VOC) first arrived in the archipelago, the Malay language was a significant trading and political language due to the influence of Malaccan Sultanate and later the Portuguese. However, the language had never been dominant among the population of Indonesian archipelagos as it was limited to mercantile activity. The VOC adopted the Malay language as the administrative language of their trading outpost in the east and thus truly began shaping the usage of Malay language on Java. The Dutch did not begin to introduce the Dutch language on the archipelago until 1799 when the Dutch crown took over the colony from the bankrupt VOC and education did not start until some time later. The Malay language remained functional as the lingua franca of the colony as there is fear that usage of Dutch language could lead to de-establishment of the colony thus it remained the language of the elite, until 1940 only 2% of the total population could speak Dutch. In this process, it absorbed a huge amount of Dutch vocabulary and loanwords. An example of this impact is the fact that today the former headquarter of the Dutch East Indies, Batavia is a Malay-speaking region in Java surrounded by areas in West Java where Sundanese is dominant.

The nationalist movement that ultimately brought Indonesian to its official status rejected Dutch from the outset. However, the rapid disappearance of Dutch was a very unusual case compared to other colonized countries, where the colonial language generally has continued to function as the language of politics, bureaucracy, education, technology, and other important areas for a significant time after independence.[16] Soenjono Dardjowidjojo even goes so far as to say that, “Indonesian is perhaps the only language that has achieved the status of a national language in its true sense” since it truly dominates in all spheres of Indonesian society (Paauw 2009). The ease with which Indonesia eliminated the language of its former oppressors can perhaps be explained as much by Dutch policy as by Indonesian nationalism, though. In marked contrast to the French, Spanish and Portuguese, who pursued an assimilationist colonial policy, or even the British, the Dutch did not attempt to spread their language among the indigenous population. In fact, they consciously prevented the language from being spread by refusing to provide education, especially in Dutch, to the native Indonesians so they would not come to see themselves as equals.[16] Moreover, the Dutch wished to prevent the Indonesians from elevating their perceived social status by taking on elements of Dutch culture. Thus, until the 1930s, they maintained a minimalist regime and unknowingly allowed Malay to spread quickly throughout the archipelago. By the time they tried to counter the spread of Malay by teaching Dutch to the natives, it was too late, and in 1942, the Japanese conquered Indonesia and outlawed the use of the Dutch language. Three years later, the Indonesians themselves formally abolished the language and established Bahasa Indonesia as the official language of the new nation.[18]

While Indonesian is spoken as a mother tongue by only a small proportion of Indonesia's large population (i.e. mainly those who reside within the vicinity of Jakarta and other large predominantly Indonesian-speaking cities such as Medan and Balikpapan), over 200 million people regularly make use of the national language, with varying degrees of proficiency. In a nation that boasts more than 300 native languages and a vast array of ethnic groups, it plays an important unifying and cross-archipelagic role for the country. Use of the national language is abundant in the media, government bodies, schools, universities, workplaces, among members of the Indonesian upper-class or nobility and also in many other formal situations, although the 2010 Indonesian Census shows that only 19.94% of people over 5 years old speak mainly Indonesian at home.[20]

Standard and formal Indonesian is used in books and newspapers and on television/radio news broadcasts; however, few native Indonesian speakers use the formal language in their daily conversations. While this is a phenomenon common to most languages in the world (for example, spoken English does not always correspond to written standards), the degree of "correctness" of spoken Indonesian (in terms of grammar and vocabulary) by comparison to its written form is noticeably low.[citation needed] This is mostly due to Indonesians combining aspects of their own local languages (e.g., Javanese, Sundanese, Balinese, and Chinese) with Indonesian.[citation needed] This results in various "regional" Indonesian dialects, the very types that a foreigner is most likely to hear upon arriving in any Indonesian city or town. This phenomenon is amplified by the use of Indonesian slang, particularly in the cities.

Indonesian is official language in Indonesia, used in all aspects, such as education. Ujian Nasional (national examination) is written in Indonesian and the language itself is one of the examination subjects.

Indonesian is also the language of Indonesian mass media, such as magazines. Printed and broadcast mass media are encouraged to use proper Indonesian, although more relaxed popular slang often prevails.

Indonesian is the official language of the Republic of Indonesia, thus its usage is encouraged throughout Indonesia. The Constitution of Indonesia 1945 Chapter XV specifies the flag, official language, coat of arms, and national anthem of Indonesia.[21] The Indonesian law No. 24 year 2009 Chapter III Section 25 to 45 specifically mentions the status of the Indonesian language.[22] Indonesian functions as a symbol of national identity and pride, and is a unifying language among the diverse Indonesian ethnic groups. It also serves as a vehicle of communication among the Indonesian provinces and different regional cultures in Indonesia.[22] The language is used as the national official language, the language of education, communication, transaction and trade documentation, the development of national culture, science, technology, and mass media in Indonesia.

According to Indonesian law, the Indonesian language is proclaimed as the unifying language during Sumpah Pemuda on 28 October 1928, developed further to accommodate the dynamics of Indonesian civilization.[22] It was mentioned that the language was based on Riau Malay,[9][23] though linguists note that this is not the local dialect of Riau, but the Malaccan dialect that was used in the Riau court.[11] Since its conception in 1928 and its official recognition in 1945 Constitution, the Indonesian language has been loaded with a nationalist political agenda to unify Indonesia (former Dutch East Indies). This status has made Indonesian language relatively open to accommodate influences from other Indonesian ethnic languages, most notably Javanese as the majority ethnic group in Indonesia, and Dutch as the previous colonizer. As a result, Indonesian has wider sources of loanwords, compared to Malay. It was suggested that the Indonesian language is an artificial language made official in 1928. By artificial it means that Indonesian was designed by academics rather than evolving naturally as most common languages have,[24] in order to accommodate the political purpose of establishing an official unifying language of Indonesia. By borrowing heavily from numerous other languages it expresses a natural linguistic evolution; in fact, it is as natural as the next language, as demonstrated in its exceptional capacity for absorbing foreign vocabulary.[24]

The disparate evolution of Indonesian and Malaysian has led to a rift between the two standards. This has been based more upon political nuance and the history of its standardization rather than cultural reasons, and as a result there are asymmetrical views regarding each other's standard among Malaysians and Indonesians. In Malaysia, the national language is Malaysian; in Indonesia, it is Indonesian. Malaysians tend to assert that Malaysian and Indonesian are merely variants of the same language, while Indonesians tend to treat them as separate, albeit related, languages. The result of this attitude is that Indonesians feel little need to harmonize their language with Malaysia and Brunei, whereas Malaysians are keener to coordinate the evolution of the language with Indonesians.[25] Although the 1972 Indonesian alphabet reform was largely a concession of Dutch-based Indonesian to the English-based spelling of Malaysian.

Indonesian is written with the Latin script. It was originally based on the Dutch spelling and still bears some similarities to it. Consonants are represented in a way similar to Italian, although ⟨c⟩ is always /tʃ/ (like English ⟨ch⟩), ⟨g⟩ is always /ɡ/ ("hard") and ⟨j⟩ represents /dʒ/ as it does in English. In addition, ⟨ny⟩ represents the palatal nasal/ɲ/, ⟨ng⟩ is used for the velar nasal/ŋ/ (which can occur word-initially), ⟨sy⟩ for /ʃ/ (English ⟨sh⟩) and ⟨kh⟩ for the voiceless velar fricative/x/. Both /e/ and /ə/ are represented with ⟨e⟩.

Spelling changes in the language that have occurred since Indonesian independence include:

Introduced in 1901, the van Ophuijsen system, (named from the advisor of the system, Charles Adriaan van Ophuijsen) was the first standardization of romanized spelling. It was most influenced by the then current Dutch spelling system. In 1947, the spelling was changed into Republican Spelling or Soewandi Spelling (named by at the time Minister of Education, Soewandi). This spelling changed formerly-spelled oe into u (however, the spelling influenced other aspects in orthography, for example writing reduplicated words). All of the other changes were a part of the Perfected Spelling System, an officially-mandated spelling reform in 1972. Some of the old spellings (which were derived from Dutch orthography) do survive in proper names; for example, the name of a former president of Indonesia is still sometimes written Soeharto, and the central Java city of Yogyakarta is sometimes written Jogjakarta.

A modern dialect of Malay, Indonesian has also borrowed from other languages, including other Austronesian languages, Sanskrit, Arabic, Persian, Portuguese, Dutch, and Chinese. It is estimated that there are some 750 Sanskrit loanwords in modern Indonesian, 1,000 Arabic loans, some of Persian and Hebrew origin, some 125 words of Portuguese (also Spanish and Italian) origin and 10,000 loanwords from Dutch[26] The vast majority of Indonesian words, however, come from the root lexical stock of its Austronesian (incl. Old Malay) heritage.[citation needed]

The study of Indonesian etymology and loan words reveals both its historical and social contexts. Examples are the early Sanskrit borrowings (probably during the Srivijaya period), the borrowings from Arabic and Persian during the time of the establishment of Islam in particular, and the ones from Dutch during the colonial period. Linguistic history and cultural history are clearly linked.[27]

The Sanskrit influence came from contacts with India since ancient times. The words were either borrowed directly from India or with the intermediary of the Old Javanese language. Although Hinduism and Buddhism are no longer the major religions of Indonesia, Sanskrit, which was the language vehicle for these religions, is still held in high esteem and is comparable with the status of Latin in English and other Western European languages. Sanskrit is also the main source for neologisms, these are usually formed from Sanskrit roots. The loanwords from Sanskrit cover many aspects of religion, art and everyday life. Sanskrit loanwords, unlike those from other languages, have entered the basic vocabulary of Indonesian to such an extent that, for many, they are no longer perceived as foreign. From Sanskrit came such words as भाषा bahasa (language), काच kaca (glass, mirror), राज- raja (king), मनुष्य manusia (mankind), भूमि bumi (earth/ world), आगम agama (religion), स्त्री Istri (wife/woman), जय Jaya (victory/victorious), पुर Pura (city/temple/place), रक्षस Raksasa (giant/monster), धर्म Dharma (rule/regulations), मन्त्र Mantra (words/poet/spiritual prayers), क्षत्रिय Satria (warrior/brave/soldier), विजय Wijaya[disambiguation needed] (greatly victorious/great victory), etc. Sanskrit words and sentences are also used in names, titles, and mottoes of the Indonesian National Police and Indonesian Armed Forces such as: Bhayangkara, Laksamana, Jatayu, Garuda, Dharmakerta Marga Reksyaka, Jalesveva Jayamahe, Kartika Eka Paksi, Swa Bhuwana Paksa, Rastra Sewakottama, Yudha Siaga, etc. The Sanskrit words also still makes the Indonesian language more powerful in meaning from the usage of the National Armed Forces titles such as (above) and more meanings that also contributes to official and formal languages of Indonesia.

The loanwords from Arabic are mainly concerned with religion, in particular with Islam, and with, by extension, greetings：for example, the word, "selamat" (from Arabic: السلام‎ salaam = peace) means "safe" or "lucky". Words of Arabic origin include dunia (from Arabic: دنيا‎ dunya = the present world), names of days (except Minggu), such as Sabtu (from Arabic: السبت‎ as-sabt = Saturday), iklan (آعلانi'lan = advertisement), kabar (خبرḵabar = news), Kursi (كرسيkursiiy = a chair), selamat/ salam (سلامsalām = a greeting), jumat (الجمعةal-jumʿa = Friday), ijazah (إجازةijāza = certificate of authority, e.g. a school diploma certificate), kitab (كتابkitāb = book), tertib (ترتيبtartīb = orderly) and kamus (قاموسqāmūs = dictionary). Allah (Arabic: الله‎), as it is mostly the case for Arabic speakers, is the word for God even in ChristianBible translations. Many early Bible translators, when they came across some unusual Hebrew words or proper names, used the Arabic cognates. In the newer translations this practice is discontinued. They now turn to Greek names or use the original Hebrew Word. For example, the name Jesus was initially translated as 'Isa (Arabic: عيسى‎), but is now spelt as Yesus. Several ecclesiastical terms derived from Arabic still exist in Indonesian language. Indonesian word for bishop is uskup (from Arabic: اسقف‎ usquf = bishop). This in turn makes the Indonesian term for archbishopuskup agung (literally great bishop), which is combining the Arabic word with an Old Javanese word. The term imam (from Arabic: امام‎ imām = leader, prayer leader) is used to translate a Catholic priest, beside its more common association with an Islamic prayer leader. Some Protestant denominations refer to their congregation jemaat (from Arabic: جماعة‎ jamā'a = group, community). Even the name of the Bible in Indonesian translation is Alkitab (from Arabic: كتاب‎ kitāb = book), which literally means "the Book".

The former colonial power, the Netherlands, left a sizable amount of vocabulary that can be seen in words such as polisi (from politie = police), kualitas (from kwaliteit = quality), rokok (from roken = smoking cigarettes), korupsi (from corruptie = corruption), kantor (from kantoor = office), resleting (from ritssluiting = zipper) and gratis (from gratis = free). These Dutch loanwords, and many other non-Italo-Iberian, European language loanwords that came via Dutch, cover all aspects of life. Some Dutch loanwords, having clusters of several consonants, pose difficulties to speakers of Indonesian. This problem is usually solved by insertion of the schwa. For example Dutch schroef[ˈsxruf] > sekrup[səˈkrup] (screw (n.)). One scholar argues that 20% of Indonesian words are inspired by the Dutch Language.[29]

Before the standardization of the language, many Indonesian words follow standard Dutch alphabet and pronunciation such as "oe" for vowel "u" or "dj" for vowel "j". As a result Malay words are written in such alphabetical order such as: "passer" for the word "Pasar" or "djalan" for the word "jalan", older Indonesian generation tend to have their name written in such order as well.

As modern Indonesian draws many of its words from foreign sources, there are many synonyms. For example, Indonesian has three words for "book", i.e. pustaka (from Sanskrit), kitab (from Arabic) and buku (from Dutch boek); however, each has a slightly different meaning.[citation needed] A pustaka is often connected with ancient wisdom or sometimes with esoteric knowledge. A derived form, perpustakaan means a library. A kitab is usually a religious scripture or a book containing moral guidance. The Indonesian words for the Bible and Gospel are Alkitab and Injil, both directly derived from Arabic. The book containing the penal code is also called the kitab. Buku is the most common word for books.

There are direct borrowings from various other languages of the world, such as "karaoke" （カラオケ） from Japanese, and "modem" from English. Many words that originally are adopted through the Dutch language today however often are mistaken as English due to the similarity of Germanic nature of both language. In some cases the words are replaced by English language through globalization, although the word "arbei" still literally means strawberry in Indonesian today the usage of the word "stroberi" is more common.

Generally Indonesian does not make use of grammatical gender, and there are only selected words that use natural gender. For instance, the same word is used for he/him and she/her (dia/ia) or for his and her (dia/ia/-nya). No real distinction is made between "girlfriend" and "boyfriend", both pacar (although more colloquial terms as cewek girl/girlfriend and cowok boy/boyfriend can also be found). A majority of Indonesian words that refer to people generally have a form that does not distinguish between the sexes. However, unlike English, distinction is made between older or younger.

There are some words that have gender, for instance putri means "daughter", and putra means "son" and also pramugara means "air steward" (male flight attendant) and pramugari meaning "air stewardess" (female flight attendant). Another example would be olahragawan, which equates to "sportsman", and olahragawati, meaning sportswoman. Often, words like these (or certain suffixes such as "-a" and "-i" or "-wan" and "wati") are absorbed from other languages (in these cases, from Sanskrit through the Old Javanese language). In some regions of Indonesia such as Sumatera and Jakarta, abang (a gender-specific term meaning "older brother") is commonly used as a form of address for older siblings/ males, while kakak (a non-gender specific term meaning "older sibling") is often used to mean "older sister". Similarly, more direct influences from other languages, such as Javanese and Chinese, have also seen further use of other gendered words in Indonesian. For example: Mas (Jav. = older brother), M'bak (Jav. = older sister), Koko (older brother) and Cici (older sister).

The most common and widely used colloquial Indonesian is heavily influenced by Betawi language, a Malay-based creole of Jakarta, amplified by its popularity in Indonesian popular culture in mass media and Jakarta's status as the national capital. In informal spoken Indonesian, various words are replaced with those of a less formal nature. For example tidak (no) is often replaced with the Javanese nggak while seperti (like, similar to) is often replaced with kayak (pronounced kai-yah). Sangat or amat (very), the term to express intensity, is often being replaced with Javanese-influenced banget.

As for pronunciation, the diphthongs ai and au on the end of base words are typically pronounced as /e/ and /o/. In informal writing the spelling of words is modified to reflect the actual pronunciation in a way that can be produced with less effort. For example, capai becomes cape or capek, pakai becomes pake, kalau becomes kalo.

In verbs, the prefix me- is often dropped, although an initial nasal consonant is often retained, as when mengangkat becomes ngangkat (the basic word is angkat). The suffixes -kan and -i are often replaced by -in. For example, mencarikan becomes nyariin, menuruti becomes nurutin. The latter grammatical aspect is one often closely related to the Indonesian spoken in Jakarta and its surrounding areas.

Over the past few years, interest in learning Indonesian has grown among non-Indonesians.[30] Various universities have started to offer courses that emphasise the teaching of the language to non-Indonesians. In addition to National Universities, private institutions have also started to offer courses, like the Indonesia Australia Language Foundation and the Lembaga Indonesia Amerika.

As early as 1988, teachers of the language have expressed the importance of a standardised Bahasa Indonesia bagi Penutur Asing (also called BIPA) materials (mostly books), and this need became more evident during the 4th International Congress on the Teaching of Indonesian to Speakers of Other Languages held in 2001.[31]

Since 2013, the Indonesian Embassy in the Philippines has given basic Indonesian language courses to 16 batches of Filipino students, as well as training to members of the Armed Forces of the Philippines. Due to increasing demand among students, the Embassy will open an intermediate Indonesian language course later in the year. The Indonesian Embassy in Washington, D.C., USA also began offering free Indonesian language courses at the beginner and intermediate level.[32]

In an interview, Department of Education Secretary Armin Luistro[33] said that the country's government should promote Indonesian or Malay, which are related to Filipino. Thus, the possibility of offering it as an optional subject in public schools is being studied.

In the Philippine game show Eat Bulaga!, Indonesian words are now also used in the segment known as Pinoy Henyo. This is became the game-show has an international franchise in Indonesia that spawned in 2012, which has reached lots of success. The Indonesian version is known as Indonesia Pintar and afterwards, the show began incorporating Indonesian words into Pinoy Henyo. On many occasions, hosts from either country visit one another's game shows, where they perform the opening and ending theme song of the game show in a mix of alternating Indonesian and Filipino.